Hey all, I'm searcing this for my brother-in-law. He has a 2002 Civic EX with a 5 speed tranny and has got a P0171 code as detected by Autozone. He has replaced the upstream O2 sensor and the light is still on. He said it mainly runs fine except when it gets down to a 1/4 tank of gas or less then it wants to hesitate at higway speeds especially going uphill. I know that alot of things could cause this code so I promised him I'd look into it before he starts throwing more money away. I know it could also be the downstream O2 sensor, a vacuum leak, a faulty gas cap, MAF sensor and so on. Just wondering if anybody has any experience with this code and what the remedy was. I appreciate any help anybody might have.

 

P0171 Fuel System Too Lean, thats what the book says

 

Advance was able to tell him that the code was too lean bank 1, but thats all. I was hoping that somebody had this code at one time and could tell me what part fixed the problem. I'm just trying to save him some money by not shotgunning parts at it or having to take it to the shop. Maybe somebody else will have some insight, thanks though for the reply.

 

Glad Im not the only one having this problem! same thing on my 02 civic on 48k miles. I was told by honda that it doesnt have a MAF, but a MAP instead.

Let me know how you get on with this, im also reluctant to throw money away replacing parts that might not be faulty. I might also start with the 02 Sensor

Good luck Man!

 

Check whether the fuel pressure is too low or high and whether the EVAP canister purge valve is leaking.

 

Hey guys,
I am new to the forum, but not new to cars. RonJ is correct. You need to check fuel pressure first before you start throwing parts at the problem. If you do not have access to a fuel pressure gauge the first thing I would check would be the fuel filter.
If the car has a over 30-40k miles and the fuel filter has not been changed it needs one anyway.
I find it funny that these parts stores will scan your car for free and then sell you a part that may not fix the problem.
Remember, if these guys had any real diagnostic expertise they would be working in a real diagnostic repair shop.
All they are really interested in is selling parts.
In my experience (22 years) this code is rarely caused by a bad O2 sensor. It is most likely a fuel delivery problem or a vacuum leak.